A lighting apparatus that produce a beam that can be steered in a desired direction remotely, for example using motors, is known for example in theatre lighting or in the home (see for example WO03/078894). However, such remote movement is mundane in nature and requires the operator to have a control unit to operate the motor to change the direction of the light beam. Also, it is hard to control the beam when the beam is directed at you or you are undertaking a task, e.g. surgery, that requires different locations to be illuminated at different times. The present invention provides a lighting apparatus and a method that allows a light beam to be directed by somebody without touching the apparatus and does not require a remote controller. Also, using the present invention, it is possible for a light beam to track the movement of a person automatically, i.e. without the need of a manually operated controller.
GB-1393794 discloses a method of lighting an actor on the stage with a spotlight. The spotlight produces a central tracker beam of non-visible radiation within the broader beam of visible radiation. The actor wears a special marker that reflects radiation from the tracker beam back to a multi-section detector. When the actor moves, reflected non-visible radiation is detected by a different section of the detector and the spotlight is moved accordingly. Such an arrangement requires the use of a special marker; also the marker may not be picked up by the detector, e.g. if the actor turns away from the spotlight. If at any stage the marker is not picked up, it is unlikely that it will be picked up later if the actor has moved.
EP-1443355 discloses a multifaceted mirror that reflects a light beam. The individual facets (or micromirrors) are each controllable so that they either direct the beam onto an object, e.g. an actor, or direct light away from the general direction of the object. The micromirrors are controlled by a processor to shape the beam so that it corresponds to the shape of the illuminated object. Movement of the object can be tracked by an operator directing the light on the object or can be tracked automatically using an automated tracking device such as “Wyborn's autopilot”, which is a device that moves the beam of a light in accordance with the movement of special markers on the object.
WO2007/110895 discloses a device for aiming a light on a target area for use, e.g. in surgery, when the target area might be in shadow from an object, e.g. the surgeon's hands or surgical instruments. The light can be moved around a circular path and wherever it is on the path, the light is directed to illuminate the same area, which will generally lie under the centre of the path. The intensity of light reflected from the illuminated area is monitored and if it decreases, e.g. because an object is in the beam casting a shadow onto the target illuminated area, the light is moved around the track to illuminate the target area from a different angle that is not obscured by the object.
U.S. Pat. No. 5,023,709 describes a lighting unit that is similar in operation to GB-1393794 for lighting an actor. An infrared tracker beam is directed at the actor who wears a special marker that reflects the incident infrared radiation back to an infrared TV camera that detects the position of the marker and moves the lighting unit if the position of the marker changes. Such an arrangement has the same disadvantages as noted for the use of special markers in connection with GB-1393794.
EP-0814344 also discloses a lighting unit for directing light on an object that can move, e.g. an actor, but avoids the use of markers by using a CCD (charge couple device) camera that picks up the image of a target to be lighted in a lighting space. An image recognition unit processes the image from the CCD camera so as to recognize the target to be lighted and specify its coordinates. A coordinate calculation unit calculates the quantity of movement of the spotlight from a quantity of movement of the target to be lighted so that the spotlight tracks the object. Unfortunately, this apparatus is highly complex and expensive and so is unsuited for application outside the field of specialist spotlight tracking.
WO-9905857 discloses a method of converting the movement of an object on a surface, e.g. a sports field, into position coordinates that may be used to control equipment, e.g. spotlights. The movement of the object on the surface is tracked from above by a person pointing a device at the moving object. From the direction of pointing, the device outputs a signal indicative of the object's position, and the equipment is operated accordingly, e.g. spotlights illuminate the object.
US-2002/0186221 discloses a device providing interaction between a person and a scene projected around the person by a computer display system. The scene and a person's (or another object's) movement and position are captured by a camera and input into the computer. The person's actions can influence the projected display scene by tracking the user's movements and altering the scene consequently. For example the display scene could include a ball; the position of the ball in the scene is known to the computer. The user's foot movement is monitored by the computer and as the foot moves towards the image of the ball in the scene (as if the user were kicking the ball), the computer alters the displayed scene is altered to move the ball in the direction that it is “kicked”.
In summary, the prior art teaches the tracking of spotlights on objects using either special markers or by shape recognition, with the disadvantages discussed above.